A path that buys time to decide where to go

This paper considers the problem of planning a path in a circumstance where its origin is given, but its destination is not specified and is to be selected from among a set of candidate destinations during a trip. A situation like this may be experienced by a group of people who have different preferred destinations, as well as by an individual who is simply indecisive about where to go. To resolve such an uncertainty, one may stay at the origin until he decides on a destination, or choose to proceed on some path that does not overly deviate from a shortest path, whichever destination is eventually chosen, and make a decision on the way. The latter action is sensible when the risk of traveling longer is outweighed by the benefit of buying more time for a better destination decision. The problem of finding such a time-buying path is formulated and a simple algorithm is developed for its solution. Some extensions and applications are also discussed.     

Cloudburst floods in mountains: State of knowledge,occurrence, factors of formation

A detailed analysis is made of the current ideas concerning floods of a special type. We examine short-lasting torrential flash floods, one of the most widespread and hazardous natural phenomena in the world characterized by a high rate of development, and by a short duration. It is established that such floods are in a primitive stage of study, which is testified by the fact that there is no general consensus as to what should be treated as a flash flood. It is pointed out that a special term designating them is also absent in many countries. It is determined that the key formation conditions for flash floods include intense short-lasting cloudbursts, the occurrence of a river basin in mountainous regions and a small drainage area; on this basis, it is suggested that they be termed flash floods. It is shown that such floods are of the most widespread occurrence in the northern hemisphere in regions with a temperate and subtropical climate. We suggest the scheme of natural factors for formation of flash floods and their differences from debris flows and floods of other types. It is determined that the main problems of investigating the formation mechanisms and forecasting the aforementioned floods are associated with the small spatiotemporal scale of these phenomena.     

Synfolding magnetization: detection, testing and geological applications

A correct method for determining the direction of a synfolding remanence is described, and a new test, which in a number of cases can discriminate between a true synfolding remanence and a remanence that is the sum of pre- and post-folding components, is suggested. It is shown that it is possible to reveal the folding evolution of a local object under an assumption that the acquisition of the synfolding remanence was synchronous over this object.     

喀斯特洞穴旅游开发

喀斯特洞穴在我国分布广泛，数量多，是一种区域性的旅游资源，通过大量的案例分析，本文阐述喀斯特洞穴资源和旅游生命周期特点，划分出孤立的，组合的，镶嵌的，介入机会的４种类型，探讨喀斯特洞穴的旅游开发问题。     

The Minkowski approach for choosing the distance metric in geographically weighted regression

In this study, the geographically weighted regression (GWR) model is adapted to benefit from a broad range of distance metrics, where it is demonstrated that a well-chosen distance metric can improve model performance. How to choose or define such a distance metric is key, and in this respect, a ‘Minkowski approach’ is proposed that enables the selection of an optimum distance metric for a given GWR model. This approach is evaluated within a simulation experiment consisting of three scenarios. The results are twofold: (1) a well-chosen distance metric can significantly improve the predictive accuracy of a GWR model; and (2) the approach allows a good approximation of the underlying ‘optimal distance metric’, which is considered useful when the ‘true’ distance metric is unknown.     

黑河流域气象要素与全球性大气环流特征量的多尺度遥相关分析

黑河流域生态-水文过程集成研究是我国近年来干旱半干旱地区的研究热点,气候变化条件下流域生态-水文过程的响应机制是其中一个重要科学问题。基于1956-2015 年黑河流域气温、湿度、降水观测数据及多个大气环流特征量监测资料,采用小波分析方法研究了流域气象要素与大气环流特征量的周期性及遥相关。结果表明：（1）流域气温与大气环流特征量的遥相关关系最为明显,湿度、降水次之。（2）气温与Niño3.4 SSTA、SOI 的显著遥相关共同周期为12～16 a,与NAO、AO为9～11 a,与WP遥相关周期为5～9 a,与PDO为8～15 a。（3）湿度与NAO遥相关周期为4～5 a,与POL为3～6 a,与WP为9～15 a,与PNA为2～8 a。（4）降水与Niño3.4 SSTA遥相关周期为9～15 a,与NAO为2～4 a,与AO为3～7 a,与POL为11～19 a,与WP为9～14 a。（5）上述各遥相关周期的地域分布、显著时段与时滞特征各有差异。本文研究有助于加深流域气象要素对环流特征量响应机制的认识,为我国干旱半干旱地区内陆河流域严峻的水-生态问题的解决及水资源管理提供依据。     

On the statistical mechanics of distributed seismicity

In order to understand the underlying physics of distributed seismicity better we have considered a 2-D array of slider blocks connected by springs and interacting via static friction with a surface. There is no driving plate in this model. The time evolution of the system is found from numerical simulations in a cellular automata formulation. Energy is conserved and is the single control parameter. The distribution of energies in the springs is found to obey a modified Maxwell-Boltzmann statistics. It is found that the number-size statistics of clusters of unstable sliding blocks is identical to those in percolation clusters in the site-to-site percolation model. There is a well-defined critical point when unstable blocks become connected across the array. It has been previously suggested that distributed seismicity in a seismic zone is the percolation backbone of a 3-D percolation cluster. The fact that low-level seismicity satisfies the Gutenberg-Richter frequency-magnitude relation and is nearly constant in time also suggests that this background seismicity is similar to thermally induced noise.     

Sudden Local Conductivity Changes in the Ionosphere

Summary. An attempt is made to describe the transient magnetic change caused by a sudden local change of conductivity in the ionosphere. In a rough illustrative model, electric current is taken to be flowing uniformly in a thin plane rigid sheet of uniform isotropic integrated conductivity, I/ϱO e.m.u. A particular type of perturbing current system is defined, and the type of conductivity anomaly which could produce it is derived. It is shown that the problem is equivalent to that of the free decay of the perturbing current system. For a very small change of conductivity, the current system is found to spread radially at a uniform rate, while decaying. The case of a large conductivity anomaly is analysed by a numerical method. It is concluded that effects at a distance would be similar to those produced by a very small change, and that near the anomaly there would be as well, a local decaying current vortex system. It is found in particular, that at a large distance L cm, the magnetic change would commence immediately and reach an extremum after time of order L × 10⁻⁶ s.     

GEOGRAPHIC NOTEBOOK: CHANGE AND GEOGRAPHY

Life is an evolution. We concentrate a period of this evolution in a stable view which we call a form, and, when the change has become considerable enough to overcome the fortunate inertia of our perception, we say that the body has changed its form. But in reality the body is changing form at every moment; or rather there is no form, since form is immobile and reality is movement. What is real is the continual change of form: form is only a snapshot view of transition.     

Mobilocality

Based on the ethnographic research and in-depth interviews in Flushing, Queens, New York City, this paper proposes the concept of mobilocality. Mobilocality provides a conceptual framework to examine the urban ethnic communities through the lens of mobility from a multi-scalar perspective. Mobilocality is formed by the paradox of transnational mobility and local immobility that are simultaneously embedded in everyday life of (im)migrants. It is through mobilocality where individual is ethnic, ethnic is transnational, transnational is urban. This article also suggests a placed and contextual understanding of mobility by illustrating the interrelationships among the four spatialities: mobility, place, scale and distance. The making of mobilocality is an outcome of the dialectal process among these spatialities, which involves not only spatial-temporal dimensions, but also social and cultural context. Transnationalism is far from a celebration of cosmopolitanism and diversity. Rather, it is a divergent process that generates heterogeneity and boundaries, a product of time-space distortion instead of time-space compression.     

地区发展水平衡量指标体系设计及实例分析

选定地区发展水平衡量指标，测度区域社会，经济，文化发展水平或发育程度是一项有重要的工作，本文试图为量度我国西部地区发展水平提供一套昼完整的指标体系，并对一个具体实例进行衡量和计算，由此说明地区的区内发展程度的差异，划分区域发展的不同类型。     

Water resources utilization and eco-environmental safety in Northwest China

Northwest China includes Xinjiang Ugyur Autonomous Region, Qinghai Province, Gansu Province, Ningxia Hui Autonomous Region and Shaanxi Province, covering 308×104 km2. It is located in the warm-temperate zone and the climate is arid or semi-arid. Precipitation is very scarce but evaporation is extremely high. The climate is dry, the water resources are deficient, the eco-environment is fragile, and the distribution of water resources is uneven. In this region, precipitation is the only input, and evaporation is the only output in the inland rivers, and precipitation, surface water and groundwater change with each other for many times, which benefits the storage and utilization of water resources. The average precipitation in this region is 232 mm, the total precipitation amount is 7003×108 m3/a, the surface water resources are 1891×108 m3/a, the total natural groundwater resources are 1150×108 m3/a, the total available water resources are 438×108 m3/a, and the total water resources are 1996×108 m3/a and per capita water resources are 2278 m3/a. The water resources of the whole area are 5.94×104 m3/(a.km2), being only one-fifth of the mean value in China. Now, the available water resources are 876×108 m3/a, among which groundwater is proximate 130×108 m3/a.     

The shifting territory of government: some insights from the Rural White Paper

Summary In this paper it is proposed that the territory of governance is currently being reconfigured by the state. The state is pulling back from a universalist, welfare role, which entailed comprehensive governance of the whole national territory. Now a much more selective form of government is coming into being, concerned with 'community', 'diversity' and 'locality'. This is not, however, simply a belated recognition by the state that these are ever more important features of socio-spatial life: rather, it is part of the reconfiguration of the territory of government as the state invokes these characteristics in order to modify its ways of governing. Using Foucault's concept of governmentality–that is the means used by the state to 'problematise' life within its territorial borders and then act on the basis of these problematisations—the recent case of the Rural White Paper is examined. It is proposed that this is a very clear example of a governmental retreat from a comprehensive role in the governance of rural areas and shows how the state now seeks to govern 'through communities'.     

A stroke-based method for automated generation of schematic network maps

This article deals with the graphic simplification of a network by schematization. A new method employing a stroke-based and progressive strategy is proposed to generate schematic network maps. This method treats a stroke (which is a long line with segments concatenated together) as a basic unit for the implementation. The procedure is as follows: (a) strokes are formed from line segments, (b) the strokes are re-orientated along grid lines and/or diagonals, and (c) two endpoints and all intersection points on (sub-)strokes are projected onto re-oriented straight lines, and (d) spatial inconsistency is detected and resolved. A methodology for each of these steps is described. This new method has been tested with a set of real-life road network data and evaluated by fractal analysis and empirical study. Experimental results show that this new method is more effective than segment-based methods and is able to produce graphics with great simplicity and clarity. Based on the results obtained, the stroke-based schematization with four primary directions is recommended.     

Spatial analysis of tilt and gravity observations of Earth tides in western Europe

Summary. Tidal gravity and tilt data are available with a great density in western Europe, so that local and regional variability of Earth tides are well documented. O1 and M2 are the most reliable waves and the relevant ocean loads are deduced from some cotidal charts and from Green's functions given by Farrell. The reliability of the charts is proved a posteriori by the convergence of O1 and M2 with respect to body tides for tilt and gravity. It is shown that a spatial trend of the gravimetric factor exists but cannot be analysed because of scatter in the data. For tilt tides the importance of the load due to the Bay of Biscay is emphasized; by considering tilt and strain powers, it is shown in a global approach that the noise is in favour of a local tilt-strain coupling, and it is proved that in each station a quantitative estimate of this phenomenon can be obtained by a statistical analysis derived from a theoretical scheme (King et al. ) in as much as the ocean load is known with sufficient accuracy; an appraisal of the diminishing tilt factor is then deduced simultaneously.     

Spatial video and GIS

GIS elemental unit representations of spatial data are often defined in terms of points, lines and areas. However, another type of spatial data that is becoming frequently captured, but as yet is largely ignored in GIS, is that of video. While digital video recording is a commonly encountered medium in modern society and encompasses many forms, from simple personal camcorders through to sophisticated survey and surveillance systems, its geographical representation in a GIS has not been fully examined or realised. In the majority of cases the video footage is usually captured while the device and/or the objects being viewed are in motion. What is of particular interest is when video streams can be, or have been, associated with spatial data such as location and orientation to create geographically referenced videographic data, which, for simplicity, will be defined as spatial video. Fundamentally, the nature of video is to record space, so when spatial properties can be accurately acquired and associated with this footage, an important geographical element can be considered for integration and analysis within a GIS.

Existing spatial video systems, both commercial and research, are predominantly used in survey or LBS roles and are usually bespoke and application specific. These systems do not model spatial video to any recognised standards that is generalised to be both data and platform independent. They do not support GIS integration and/or analysis from a purely spatial content perspective. A video-image/remote-sensing centric approach prevails where usage options range from simple visualisation interfaces to interactive computer vision systems. What has been largely overlooked is a spatial approach where the inherent geographical extent recorded in each video frame can be modelled and used in a geo-spatial analysis context. While this modelling approach has not been fully realised, it does exist in a GIS form based on Open Geospatial Consortium standards, where the spatial context of video is defined in a structure called a ViewCone. However, a ViewCone only defines a 2D model of the geographical extent of each frame and is restricted to a three-or-five sided polygon representation.

Thus, this article examines the potential of modelling spatial video through the use of elemental data types within GIS; gives some examples of using this approach; describes some problems in using spatial video within GIS; and then demonstrates how these problems are being solved. This is done in three stages: Firstly, a detailed overview of spatial video in its current GIS role is provided – this is achieved through a complete introduction to the distinct elements of spatial video followed by a review of its use in both commercial and academic application areas. Secondly, a brief theoretical overview of an alternative GIS-constrained ViewCone data structure is given that defines a more flexible spatial video model for both 2D and 3D GIS analysis and visualisation. Thirdly, a selective sample of results is presented based on an implementation of this approach being applied to a constrained spatial video data source in a specific study area.     

极化还是均衡:重塑大国经济地理的战略选择——城市规模分布变化和影响因素的跨国分析

关于国家空间发展战略,经济学家主张要素向中国沿海发达地区自由流动,而城市和经济地理学家则认为应对不发达地区发展给予支持。本文以国家尺度的城市规模分布来测度经济地理格局和城市化空间结构,综合运用截面和面板双重估计方法,探索了国家经济地理格局与国家规模的关系。结论显示,在控制了其他因素后,表征国家规模的人口规模和国土面积与国家经济地理的均衡分布呈现显著正相关,即大国的经济地理倾向于多中心均衡布局。机制在于,经济中心的辐射半径不是无限的,地理或者更准确地说是距离对于生产力和城市化布局具有重要作用。此外,随着经济水平的提高,国家经济地理格局呈现先极化后均衡的演化趋势;城市化率和非农产业比重的提高以及稳定的政治环境同样也会促进国家经济地理格局向均衡方向发展。再考虑到国家安全、社会稳定的政治诉求和中国地大物博的既有现实,本文政策启示是,大国的经济地理和城市化格局应该走适度均衡发展之路,国家采取空间干预政策促进中国不发达地区的发展有其合理性和必要性。     

The influence of land use change on karst water quality of Shuicheng Basin in Guizhou Province

The influence of land use and land cover on ecological environment is a focus of global change research. The paper chooses an industrial city-Shuicheng in Guizhou Province-as a study area because the karst water quality around the city is deteriorating with land use and land cover change. The natural susceptibility of karst water system is an important factor leading to karst water pollution. But land use and land cover change is also a main factor according to the chemical analysis of karst water quality and land use change. So it is a good way to protect karst water through rational planning and managing of land use and land cover.     

Towards distributed e-map service

This paper explores a new approach towards the distributed e-map service with CORBA. The architecture of a distributed e-map service model is described. This model mainly contains a distributed map database, a database connection layer, an application service layer and a client layer. For the sake of convenient transmission of map data, a combination of CORBA and GML method is introduced. Furthermore, in order to keep the loading balance among distributed servers, object migration is implemented among servers and security is considered.     

A method for assessing regional debris flow risk: an application in Zhaotong of Yunnan province (SW China)

Based on the definitions of the United Nations, the assessment of risk involves the evaluation of both hazard and vulnerability. This forms the basis of a generalized assessment model of debris flow risk. Hazard is a measure of the threatening degree of an extreme event and is expressed theoretically as a function of event magnitude and frequency of occurrence. Mathematically, it is the definite integral area under the magnitude–frequency curve. Based on the need for a model applicable in regions that lack data, a new method that incorporates theoretical concepts with empirical analysis is presented to calculate the regional hazardousness of debris flows. Debris flow hazard can be estimated from gully density, mean annual rainfall and percentage of cultivated land on steep slope. Vulnerability is defined as the potential total maximum losses due to a potential damaging phenomenon for a specified area and during a reference period. On a regional scale, it is dependent on the fixed assets, gross domestic product, land resources and population density, as well as age, education and wealth of the inhabitants. A nonlinear, power-function model to compute the vulnerability degree is presented. An application of the proposed method to Zhaotong prefecture of Yunnan province, SW China, provides high accuracy and reasonable risk estimates. The highest risk of debris flow is in Zhaotong county with a value of 0.48; the lowest risk of debris flow is in Yanjin county with a value of 0.16. The other counties have debris flow risks ranging from 0.22 to 0.46. This provides an approach for assessing the regional debris flow risk and a basis for the formulation of a regional risk management policy in Zhaotong prefecture.